Desacetyl-?-melanocyte stimulating hormone and ?-melanocyte stimulating hormone are required to regulate energy balance.

ABSTRACT:

Objective

Regulation of energy balance depends on pro-opiomelanocortin (POMC)-derived peptides and melanocortin-4 receptor (MC4R). Alpha-melanocyte stimulating hormone (?-MSH) is the predicted natural POMC-derived peptide that regulates energy balance. Desacetyl-?-MSH, the precursor for ?-MSH, is present in brain and blood. Desacetyl-?-MSH is considered to be unimportant for regulating energy balance despite being more potent (compared with ?-MSH) at activating the appetite-regulating MC4R in vitro. Thus, the physiological role for desacetyl-?-MSH is still unclear.

Methods

We created a novel mouse model to determine whether desacetyl-?-MSH plays a role in regulating energy balance. We engineered a knock in targeted QKQR mutation in the POMC protein cleavage site that blocks the production of both desacetyl-?-MSH and ?-MSH from adrenocorticotropin (ACTH_1-39).

Results

The mutant ACTH_1-39 (ACTH^QKQR) functions similar to native ACTH_1-39 (ACTH^KKRR) at the melanocortin 2 receptor (MC2R) in vivo and MC4R in vitro. Male and female homozygous mutant ACTH_1-39 (Pomc^tm1/tm1) mice develop the characteristic melanocortin obesity phenotype. Replacement of either desacetyl-?-MSH or ?-MSH over 14 days into Pomc^tm1/tm1 mouse brain significantly reverses excess body weight and fat mass gained compared to wild type (WT) (Pomc^wt/wt) mice. Here, we identify both desacetyl-?-MSH and ?-MSH peptides as regulators of energy balance and highlight a previously unappreciated physiological role for desacetyl-?-MSH.

Conclusions

Based on these data we propose that there is potential to exploit the naturally occurring POMC-derived peptides to treat obesity but this relies on first understanding the specific function(s) for desacetyl-?-MSH and ?-MSH.

SUBMITTER: Mountjoy KG 

PROVIDER: S-EPMC5869732 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature